diff --git a/benchmark/ICSharpCode.SharpZipLib.Benchmark/ICSharpCode.SharpZipLib.Benchmark.csproj b/benchmark/ICSharpCode.SharpZipLib.Benchmark/ICSharpCode.SharpZipLib.Benchmark.csproj
index 7fa26f80f..a6d73c8db 100644
--- a/benchmark/ICSharpCode.SharpZipLib.Benchmark/ICSharpCode.SharpZipLib.Benchmark.csproj
+++ b/benchmark/ICSharpCode.SharpZipLib.Benchmark/ICSharpCode.SharpZipLib.Benchmark.csproj
@@ -3,6 +3,7 @@
 	<PropertyGroup>
 		<OutputType>Exe</OutputType>
 		<TargetFrameworks>net462;net6.0</TargetFrameworks>
+		<LangVersion>8.0</LangVersion>
 	</PropertyGroup>
 
 	<ItemGroup>
diff --git a/benchmark/ICSharpCode.SharpZipLib.Benchmark/Tar/TarInputStream.cs b/benchmark/ICSharpCode.SharpZipLib.Benchmark/Tar/TarInputStream.cs
index b59a217ab..08116bfe5 100644
--- a/benchmark/ICSharpCode.SharpZipLib.Benchmark/Tar/TarInputStream.cs
+++ b/benchmark/ICSharpCode.SharpZipLib.Benchmark/Tar/TarInputStream.cs
@@ -27,7 +27,7 @@ public TarInputStream()
 					tarEntry.Size = 1024 * 1024;
 					zipOutputStream.PutNextEntry(tarEntry);
 
-					var rng = RandomNumberGenerator.Create();
+					using var rng = RandomNumberGenerator.Create();
 					var inputBuffer = new byte[1024];
 					rng.GetBytes(inputBuffer);
 
diff --git a/benchmark/ICSharpCode.SharpZipLib.Benchmark/Zip/ZipOutputStream.cs b/benchmark/ICSharpCode.SharpZipLib.Benchmark/Zip/ZipOutputStream.cs
index c4e8620e3..b6789afb5 100644
--- a/benchmark/ICSharpCode.SharpZipLib.Benchmark/Zip/ZipOutputStream.cs
+++ b/benchmark/ICSharpCode.SharpZipLib.Benchmark/Zip/ZipOutputStream.cs
@@ -27,7 +27,7 @@ public long WriteZipOutputStream()
 		{
 			using (var memoryStream = new MemoryStream(outputBuffer))
 			{
-				var zipOutputStream = new SharpZipLib.Zip.ZipOutputStream(memoryStream);
+				using var zipOutputStream = new SharpZipLib.Zip.ZipOutputStream(memoryStream);
 				zipOutputStream.PutNextEntry(new SharpZipLib.Zip.ZipEntry("0"));
 
 				for (int i = 0; i < ChunkCount; i++)
diff --git a/src/ICSharpCode.SharpZipLib/Encryption/ZipAESStream.cs b/src/ICSharpCode.SharpZipLib/Encryption/ZipAESStream.cs
index 346b5484b..d255db3a9 100644
--- a/src/ICSharpCode.SharpZipLib/Encryption/ZipAESStream.cs
+++ b/src/ICSharpCode.SharpZipLib/Encryption/ZipAESStream.cs
@@ -48,7 +48,7 @@ public ZipAESStream(Stream stream, ZipAESTransform transform, CryptoStreamMode m
 		// total length of block + auth code
 		private const int BLOCK_AND_AUTH = CRYPTO_BLOCK_SIZE + AUTH_CODE_LENGTH;
 
-		private Stream _stream;
+		private readonly Stream _stream;
 		private ZipAESTransform _transform;
 		private byte[] _slideBuffer;
 		private int _slideBufStartPos;
diff --git a/src/ICSharpCode.SharpZipLib/Encryption/ZipAESTransform.cs b/src/ICSharpCode.SharpZipLib/Encryption/ZipAESTransform.cs
index 32c7b8156..6f7c0ba15 100644
--- a/src/ICSharpCode.SharpZipLib/Encryption/ZipAESTransform.cs
+++ b/src/ICSharpCode.SharpZipLib/Encryption/ZipAESTransform.cs
@@ -51,11 +51,11 @@ public ZipAESTransform(string key, byte[] saltBytes, int blockSize, bool writeMo
 
 			// Performs the equivalent of derive_key in Dr Brian Gladman's pwd2key.c
 #if NET472_OR_GREATER || NETSTANDARD2_1_OR_GREATER || NETCOREAPP2_0_OR_GREATER
-			var pdb = new Rfc2898DeriveBytes(key, saltBytes, KEY_ROUNDS, HashAlgorithmName.SHA1);
+			using var pdb = new Rfc2898DeriveBytes(key, saltBytes, KEY_ROUNDS, HashAlgorithmName.SHA1);
 #else
-			var pdb = new Rfc2898DeriveBytes(key, saltBytes, KEY_ROUNDS);
+			using var pdb = new Rfc2898DeriveBytes(key, saltBytes, KEY_ROUNDS);
 #endif
-			var rm = Aes.Create();
+			using var rm = Aes.Create();
 			rm.Mode = CipherMode.ECB;           // No feedback from cipher for CTR mode
 			_counterNonce = new byte[_blockSize];
 			byte[] key1bytes = pdb.GetBytes(_blockSize);
@@ -171,7 +171,11 @@ public byte[] TransformFinalBlock(byte[] inputBuffer, int inputOffset, int input
 		/// <summary>
 		/// Cleanup internal state.
 		/// </summary>
-		public void Dispose() => _encryptor.Dispose();
+		public void Dispose()
+		{
+			_encryptor.Dispose();
+			_hmacsha1.Dispose();
+		}
 
 		#endregion ICryptoTransform Members
 	}
diff --git a/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj b/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj
index 49a1cd5cd..26c168f68 100644
--- a/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj
+++ b/src/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj
@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net6.0</TargetFrameworks>
+		<LangVersion>8.0</LangVersion>
     <IsTrimmable>true</IsTrimmable>
     <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
     <SignAssembly>true</SignAssembly>
diff --git a/src/ICSharpCode.SharpZipLib/Zip/ZipFile.cs b/src/ICSharpCode.SharpZipLib/Zip/ZipFile.cs
index 7fc1c5592..5b839dd01 100644
--- a/src/ICSharpCode.SharpZipLib/Zip/ZipFile.cs
+++ b/src/ICSharpCode.SharpZipLib/Zip/ZipFile.cs
@@ -863,7 +863,7 @@ public int FindEntry(string name, bool ignoreCase)
 			// TODO: This will be slow as the next ice age for huge archives!
 			for (int i = 0; i < entries_.Length; i++)
 			{
-				if (string.Compare(name, entries_[i].Name, ignoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal) == 0)
+				if (string.Equals(name, entries_[i].Name, ignoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal))
 				{
 					return i;
 				}
@@ -1208,7 +1208,7 @@ private long TestLocalHeader(ZipEntry entry, HeaderTest tests)
 				byte[] extraData = new byte[extraDataLength];
 				StreamUtils.ReadFully(baseStream_, extraData);
 
-				var localExtraData = new ZipExtraData(extraData);
+				using var localExtraData = new ZipExtraData(extraData);
 
 				// Extra data / zip64 checks
 				if (localExtraData.Find(headerID: 1))
@@ -2249,7 +2249,7 @@ private void WriteLocalEntryHeader(ZipUpdate update)
 				throw new ZipException("Entry name too long.");
 			}
 
-			var ed = new ZipExtraData(entry.ExtraData);
+			using var ed = new ZipExtraData(entry.ExtraData);
 
 			if (entry.LocalHeaderRequiresZip64)
 			{
@@ -2360,7 +2360,7 @@ private int WriteCentralDirectoryHeader(ZipEntry entry)
 			WriteLEShort(name.Length);
 
 			// Central header extra data is different to local header version so regenerate.
-			var ed = new ZipExtraData(entry.ExtraData);
+			using var ed = new ZipExtraData(entry.ExtraData);
 
 			if (entry.CentralHeaderRequiresZip64)
 			{
@@ -3795,7 +3795,7 @@ private Stream CreateAndInitDecryptionStream(Stream baseStream, ZipEntry entry)
 			{
 				if (entry.Version < ZipConstants.VersionStrongEncryption || !entry.HasFlag(GeneralBitFlags.StrongEncryption))
 				{
-					var classicManaged = new PkzipClassicManaged();
+					using var classicManaged = new PkzipClassicManaged();
 
 					OnKeysRequired(entry.Name);
 					if (HaveKeys == false)
@@ -3821,7 +3821,7 @@ private Stream CreateAndInitEncryptionStream(Stream baseStream, ZipEntry entry)
 			if (entry.Version >= ZipConstants.VersionStrongEncryption &&
 			    entry.HasFlag(GeneralBitFlags.StrongEncryption)) return null;
 
-			var classicManaged = new PkzipClassicManaged();
+			using var classicManaged = new PkzipClassicManaged();
 
 			OnKeysRequired(entry.Name);
 			if (HaveKeys == false)
diff --git a/src/ICSharpCode.SharpZipLib/Zip/ZipOutputStream.cs b/src/ICSharpCode.SharpZipLib/Zip/ZipOutputStream.cs
index 2cc36df22..e2908aa4a 100644
--- a/src/ICSharpCode.SharpZipLib/Zip/ZipOutputStream.cs
+++ b/src/ICSharpCode.SharpZipLib/Zip/ZipOutputStream.cs
@@ -766,7 +766,7 @@ private byte[] CreateZipCryptoHeader(long crcValue)
 		/// <param name="password">The password.</param>
 		private void InitializeZipCryptoPassword(string password)
 		{
-			var pkManaged = new PkzipClassicManaged();
+			using var pkManaged = new PkzipClassicManaged();
 			byte[] key = PkzipClassic.GenerateKeys(ZipCryptoEncoding.GetBytes(password));
 			cryptoTransform_ = pkManaged.CreateEncryptor(key, null);
 		}